Soulanille, Elaine

Introduction

Ascidians are sessile marine invertebrates, occurring throughout the world, usually in shallow waters and attached to hard surfaces. The family includes over 2000 described species, many of which are colonial -- along with some of the Thaliacea, the only colonial chordates. When disturbed, ascidians often forcibly eject water from their siphons -- the reason for their common name, "sea squirts."